Top furling automated retractable greenhouse cover

ABSTRACT

Top furling automated retractable greenhouse cover is a retractable cover for a greenhouse that is mounted on top of the greenhouse. Top furling automated retractable greenhouse cover has: a spine clamp, a left furling cover assembly, a right furling cover assembly, a hinge pin assembly, and an electrical control box. Left and right furling assemblies each have a curtain or cover, a furling rod, a furling motor, and a support arm. Electrical control box sends electronic signals to cause left and right covers or curtains to furl above the greenhouse when retracted and to unfurl down to the ground when extended to cover the greenhouse. The top-mounted design allows efficient use of gravity to apply tension to the furled rolls.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a retractable cover or curtain for agreenhouse and specifically to a top furling automated retractable coveror curtain for a greenhouse that retracts onto two rolls, each adjacentto and parallel to the ridge line of the roof and the greenhouse.

2. Description of Related Art

A greenhouse is a building in which plants are grown. Growing plants ina building is advantageous because the interior of a building can besheltered from the exterior to allow for easier climate control of theinterior in a manner that is more conducive to plant growth. Typically,the roof and walls of a greenhouse are made of impermeable andtransparent or translucent material. The transparent or translucentaspect of the material allows light and energy from the sun to penetratethe roof and walls of the greenhouse in order to shine light and energyonto the plants and interior of the greenhouse. Light and energy areused to grow the plants as is required with the photosynthesis processand are also used to heat the interior of the greenhouse as light andenergy are absorbed by the plants and interior of the greenhouse toradiate heat inside the greenhouse. The impermeable aspect of thematerial acts to shelter the plants and interior of the greenhouse fromoutside weather such as wind, rain, sleet, snow, and the like, to retainthe radiated heat from the interior of the greenhouse, and to retainevaporated water vapor within the interior of the greenhouse for plantwatering recycling.

There are instances where it is desirable to extend a special cover orcurtain over the existing impermeable and transparent or translucentmaterial of a greenhouse. When exterior temperatures are lower thanoptimal for plant growth, an insulated cover can be used to help retainmore heat within the interior of the greenhouse, thereby keeping optimalgrowth temperatures for longer periods of time. When exteriortemperatures are higher than optimal for plant growth, a solar shadecover can be used to block or reduce the amount of light and energypassing into the interior of the greenhouse, which in turn helps reducethe interior temperature of the greenhouse. In order to control thegrowth stage of the plants, a completely opaque cover can be used toblock out all light and energy from passing through the greenhouse atcertain times of day to artificially change the length of day perceivedby the plants, which designates certain growth cycles within the plants.

There also instances where it is desirable to retract the special coveror curtain from covering the greenhouse and/or to retract the existingimpermeable and transparent or translucent material from covering thegreenhouse. When the interior temperatures of the greenhouse are higherthan optimal, the insulated cover can be removed to help release moreheat from the interior of the greenhouse, thereby keeping optimal growthtemperatures for longer periods of time. When the interior temperaturesof the greenhouse are lower than optimal, the solar shade cover can beremoved to increase the amount of light and energy passing into theinterior of the greenhouse, which in turn helps increase the interiortemperature of the greenhouse. In order to provide maximum airventilation for the plants, all coverings and barriers could be removedfrom the roof and walls of the greenhouse. In order to provide maximumheat loss through radiation into the outside air, all coverings andbarriers could be removed from the roof and walls of the greenhouse.

This invention is a retractable greenhouse cover that can be used toreversibly extend a cover or curtain over the roof and sidewalls of agreenhouse in order to provide an insulated cover and/or a solar shadecover for the greenhouse. In addition, the retractable greenhouse coverof this invention can be used to reversibly extend the impermeable andtransparent or translucent material over the frame of the greenhouse inorder to install and retract all covering from the roof and sidewalls ofthe greenhouse. There are other retractable greenhouse covers in theprior art, but none that use a top-furling dual-awning mechanism thatcan reversibly extend any type of cover or curtain material over theroof and sidewalls of a greenhouse as shown and described here.

BRIEF SUMMARY OF THE INVENTION

In is an aspect of top furling automated retractable greenhouse cover toreversibly extend a cover or curtain over the roof and sidewalls of anexisting greenhouse.

In is an aspect of top furling automated retractable greenhouse cover toprovide two furlable covers or curtains, where each cover or curtainincludes a furling and unfurling mechanism to furl and unfurl thecurtain or cover.

It is an aspect of each furling mechanism to reversibly wind a cover orcurtain into a roll that is positioned above the roof of the greenhouse,with the roll adjacent and parallel to the longitudinal ridge of theroof of the greenhouse.

In is an aspect of each furling mechanism to reversibly unwind a coveror curtain from the roll position above the roof of the greenhouse tothe ground.

It is an aspect of each furling mechanism to include a furling rod and afurling motor.

In is an aspect of each cover or curtain to be a sheet of flexiblematerial with one end rigidly attached to the longitudinal ridge of theroof of the greenhouse and the opposite end rigidly attached to thefurling rod of the furling mechanism.

It is an aspect of each furling mechanism for gravity to provide tensionbetween the attached end on the roof of the greenhouse and the furledroll at the other end.

It is an aspect of each furling mechanism to provide smooth and reliablefurling and unfurling of a cover or curtain over a greenhouse withstraight sidewalls.

In is an aspect of each cover or curtain to be permeable or impermeable.

In is an aspect of each cover or curtain to be transparent, translucent,or opaque.

In is an aspect of each cover or curtain to be insulated or uninsulated.

In is an aspect of top furling automated retractable greenhouse cover toinclude an electrical control box that is in electrical continuity witheach furling motor and a power source.

In is an aspect each furling mechanism to be electronically controlledby the control box to extend or unfurl at certain times of day.

In is an aspect each furling mechanism to be electronically controlledby the control box to extend or unfurl under certain environmentalconditions such as temperature, humidity, wind, precipitation, etc.

In is an aspect each furling mechanism to be electronically controlledby the control box to retract or furl at certain times of day.

In is an aspect each furling mechanism to be electronically controlledby the control box to retract or furl under certain environmentalconditions such as temperature, humidity, wind, precipitation, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of top furling automated retractablegreenhouse cover installed over a Quonset or rounded sidewall greenhousewith the cover or curtain fully retracted and furled.

FIG. 2 is a perspective view of top furling automated retractablegreenhouse cover installed over a Quonset or rounded sidewall greenhousewith the cover or curtain fully extended and unfurled.

FIG. 3 is a front elevation view of top furling automated retractablegreenhouse cover installed over a Quonset or rounded sidewall greenhousewith the cover or curtain fully retracted and furled.

FIG. 4 is a front elevation view of top furling automated retractablegreenhouse cover installed over a Quonset or rounded sidewall greenhousewith the cover or curtain partially extended and unfurled.

FIG. 5 is a front elevation view of top furling automated retractablegreenhouse cover installed over a Quonset or rounded sidewall greenhousewith the cover or curtain fully extended and unfurled.

FIG. 6 is a perspective view of top furling automated retractablegreenhouse cover installed over a Semi-Gabled or straight sidewallgreenhouse with the cover or curtain fully retracted and furled.

FIG. 7 is a perspective view of top furling automated retractablegreenhouse cover installed over a Semi-Gabled or straight sidewallgreenhouse with the cover or curtain fully extended and unfurled.

FIG. 8 is a front elevation view of top furling automated retractablegreenhouse cover installed over a Semi-Gabled or straight sidewallgreenhouse with the cover or curtain fully retracted and furled.

FIG. 9 is a front elevation view of top furling automated retractablegreenhouse cover installed over a Semi-Gabled or straight sidewallgreenhouse with the cover or curtain partially extended and unfurled.

FIG. 10 is a front elevation view of top furling automated retractablegreenhouse cover installed over a Semi-Gabled or straight sidewallgreenhouse with the cover or curtain fully extended and unfurled.

FIG. 11 is a blowup view of the top ends of left support arm and rightsupport arm and a blowup view of the bottom ends of left support arm andright support arm.

DEFINITION LIST

Term Definition 5 Top Furling Automated Retractable Greenhouse Cover 10Spine Clamp 20 Left Furling Cover Assembly 22 Left Cover or Curtain 24Left Furling Rod 26 Left Furling Motor 28 Left Support Arm 29 Hinge PinSocket 30 Right Furling Cover Assembly 32 Right Cover or Curtain 34Right Furling Rod 36 Right Furling Motor 38 Right Support Arm 39 HingePin Socket 40 Hinge Pin Assembly 42 Hinge Pin 44 Hinge Pin Bracket 46Bracket Base 50 Electrical Control Box 55 Electrical Wiring 60 SupportArm Extension 63 Hinge Pin Socket 66 Support Arm Extension Spring 100Existing Greenhouse

DETAILED DESCRIPTION OF THE INVENTION

Top furling automated retractable greenhouse cover 5 comprises: a spineclamp 10, a left furling cover assembly 20, a right furling coverassembly 30, a hinge pin assembly 40, and an electrical control box 50.Top furling automated retractable greenhouse cover 5 attaches to anexisting greenhouse 100 to provide an automated retractable cover orcurtain extending over the roof and sidewalls of the existing greenhouse100. Existing greenhouse 100 may have its own greenhouse cover (notdepicted), in which case the top furling automated retractablegreenhouse cover 5 provides a second exterior cover or curtain over theroof and sidewalls of the greenhouse 100. Alternately, existinggreenhouse 100 may not have a cover and consist of a frame only (asdepicted) in which case the top furling automated retractable greenhousecover 5 provides a singular exterior cover or curtain over the roof andsidewalls of the greenhouse 100.

Left furling cover assembly 20 comprises: a left cover or curtain 22, aleft furling rod 24, a left furling motor 26, and a left support arm 28.Left cover or curtain 22 is a rectangular sheet of flexible materialwith a right edge, a left edge, a top edge, and a bottom edge. Therectangular sheet has a length that is about 0.5-10 feet longer thanthat of greenhouse 100 and a width of about that of the greenhouse 100.Thus, any length and/or width greenhouse can be accommodated with thisinvention. The right and left edges are the widths of the rectangularsheet and the top and bottom edges are the lengths rectangular sheet.Flexible material may be permeable to the wind, rain, weather, and thelike. Flexible material may be impermeable to the wind, rain, weather,and the like. Flexible material may be insulated or uninsulated.Flexible material may be completely transparent to transmit all sunlightor translucent to partially block sunlight. Flexible material may becompletely opaque to block all sunlight from passing through it.Flexible material must be weather resistant and capable of survivingextended exposure to sun, wind, rain, weather, and the like withoutdegrading. Flexible material may be made of any known material such asplastic material, woven fabric, nonwoven fabric, flexible sheetmaterial, composite, quilting, blanketing, insulation, extrusion, orcoextrusion.

Left furling rod 24 is a rigid or semi-rigid cylindrical member with afirst end and a second end. Cylindrical member may be solid or hollow.The length of the cylindrical member should be about 0.5-10 feet longerthan the length of the existing greenhouse 100 to be covered.Cylindrical member must be sturdy, strong, and capable of supportinghundreds of pounds of weight without breaking, cracking or deforming.Cylindrical member may be made of any known material such as metal,plastic, composite, wood, or ceramic.

Left furling motor 26 is an electric motor with a housing and adriveshaft. An electric motor is an electrically powered rotary devicethat rotates a driveshaft when electrically powered. One end of thedriveshaft is located within the housing of the motor and the other endof the driveshaft extends out of the housing. When an electric motor iselectrically powered on, the driveshaft rotates while the housingremains stationary. Left furling motor 26 is capable of rotating itsdriveshaft in a specific amount of revolutions in the counterclockwisedirection when a certain electronic command is received. Left furlingmotor 26 is capable of rotating its driveshaft in a specific amount ofrevolutions in the clockwise direction when another electronic commandis received. The first end of left furling rod 24 is rigidly attachedend-to-end and parallel to the exposed end of the driveshaft of leftfurling motor 26 so that left furling rod 24 rotates commensurately andin unison with the driveshaft of the left furling motor 26. Rigidattachment of left furling rod 24 to the exposed end of the driveshaftmay be accomplished by any known means such as clamping, welding,gluing, soldering, bolting, or screwing.

Left furling motor 26 is capable of receiving a ‘furl signal’ fromelectrical control box 50 and, in response, furl the left cover orcurtain 22 from the unfurled position into the furled, retractedposition and to stop furling upon reaching a set position of the furledroll. If left furling motor 26 receives a ‘furl signal’ when it isalready in the furled position, it disregards the furl signal and doesnothing. Left furling motor 26 is capable of receiving a ‘unfurl signal’from electrical control box 50 and, in response, unfurl the left coveror curtain 22 from the furled position into the unfurled extendedposition and to stop unfurling upon reaching a set position of theunfurled roll. If left furling motor 26 receives a ‘unfurl signal’ whenit is already in the extended position it disregards the unfurl signaland does nothing.

The left furling motor 26 and the left furling rod 24 are supportedabove the ground by the left support arm 28. Left support arm 28 is arigid or semi-rigid cylindrical member with a bottom end and a top end.Cylindrical member may be solid or hollow. The length of the cylindricalmember should be about 0.5-10 feet longer than the height of theexisting greenhouse 100 to be covered. The top end of left support arm28 is rigidly attached to the housing of left furling motor 26. Rigidattachment may be accomplished by any known means such as such asclamping, welding, gluing, soldering, bolting, or screwing. The bottomend of left support arm 28 has a hinge pin socket 63. Hinge pin socket63 is a cylindrical hole through left support arm 28 that isperpendicular to the longitudinal axis of left support arm 28. The innerdiameter of hinge pin socket 63 is sized to form a slip fit with theouter diameter of hinge pin 42. The bottom end of left support arm 28 ispivotally attached to hinge pin assembly 40 with hinge pin 42 positionedthrough hinge pin socket 63.

Right furling cover assembly 30 comprises: a right cover or curtain 32,a right furling rod 34, a right furling motor 36, and a right supportarm 38. Right cover or curtain 32 is a rectangular sheet of flexiblematerial with a right edge, a right edge, a top edge, and a bottom edge.The rectangular sheet has a length that is about 0.5-10 feet longer thanthat of greenhouse 100 and a width of about that of the greenhouse 100.The right and left edges are the widths of the rectangular sheet and thetop and bottom edges are the lengths rectangular sheet. Flexiblematerial may be permeable to the wind, rain, weather, and the like.Flexible material may be impermeable to the wind, rain, weather, and thelike. Flexible material may be insulated or uninsulated. Flexiblematerial may be completely transparent to transmit all sunlight ortranslucent to partially block sunlight. Flexible material may becompletely opaque to block all sunlight from passing through it.Flexible material must be weather resistant and capable of survivingextended exposure to sun, wind, rain, weather, and the like withoutdegrading. Flexible material may be made of any known material such asplastic material, woven fabric, nonwoven fabric, flexible sheetmaterial, composite, quilting, blanketing, insulation, extrusion, orcoextrusion.

Right furling rod 34 is a rigid or semi-rigid cylindrical member with afirst end and a second end. Cylindrical member may be solid or hollow.The length of the cylindrical member should be about 0.5-10 feet longerthan the length of the existing greenhouse 100 to be covered. Right andleft furling rods 24,34 have equal lengths. Cylindrical member must besturdy, strong, and capable of supporting hundreds of pounds of weightwithout breaking, cracking or deforming. Cylindrical member may be madeof any known material such as metal, plastic, composite, wood, orceramic.

Right furling motor 36 is an electric motor with a housing and adriveshaft. An electric motor is an electrically powered rotary devicethat rotates a driveshaft when electrically powered. One end of thedriveshaft is located within the housing of the motor and the other endof the driveshaft extends out of the housing. When an electric motor iselectrically powered on, the driveshaft rotates while the housingremains stationary. Right furling motor 36 is capable of rotating itsdriveshaft in a specific amount of revolutions in the clockwisedirection when a certain electronic command is received. Right furlingmotor 36 is capable of rotating its driveshaft in a specific amount ofrevolutions in the counterclockwise direction when another electroniccommand is received. The first end of right furling rod 34 is rigidlyattached end-to-end and parallel to the exposed end of the driveshaft ofright furling motor 36 so that right furling rod 34 rotatescommensurately and in unison with the driveshaft of the right furlingmotor 36. Rigid attachment of right furling rod 34 to the exposed end ofthe driveshaft may be accomplished by any known means such as clamping,welding, gluing, soldering, bolting, or screwing.

Right furling motor 36 is capable of receiving a ‘furl signal’ fromelectrical control box 50 and, in response, furl the right cover orcurtain 32 from the unfurled position into the furled retracted positionand to stop furling upon reaching a set position of the furled roll. Ifright furling motor 36 receives a ‘furl signal’ when it is already inthe furled position, it disregards the furl signal and does nothing.Right furling motor 36 is capable of receiving a ‘unfurl signal’ fromelectrical control box 50 and, in response, unfurl the right cover orcurtain 32 from the furled position into the unfurled extended positionand to stop unfurling upon reaching a set position of the unfurled roll.If right furling motor 36 receives a ‘unfurl signal’ when it is alreadyin the extended position, it disregards the unfurl signal and doesnothing.

The right furling motor 36 and the right furling rod 34 are supportedabove the ground by the right support arm 38. Right support arm 38 is arigid or semi-rigid cylindrical member with a bottom end and a top end.Cylindrical member may be solid or hollow. The length of the cylindricalmember should be about 0.5-10 feet longer than the height of theexisting greenhouse 100 to be covered. The top end of right support arm38 is rigidly attached to the housing of right furling motor 36.Attachment may be accomplished by any known means such as such asclamping, welding, gluing, soldering, bolting, or screwing. The bottomend of right support arm 38 has a hinge pin socket 63. Hinge pin socket63 is a cylindrical hole through right support arm 38 that isperpendicular to the longitudinal axis of right support arm 38. Theinner diameter of hinge pin socket 63 is sized to form a slip fit withthe outer diameter of hinge pin 42. The bottom end of right support arm38 is pivotally attached to hinge pin assembly 40 with hinge pin 42positioned through hinge pin socket 63.

Hinge pin assembly 40 comprises: a hinge pin 42 and at least one hingepin bracket 44. Hinge pin assembly 40 pivotally attaches the bottom endsboth the left and right support arms 28,38 to the ground. Pivotalattachment of both support arms 28 and 38 can be accomplished with onehinge pin assembly 40 located at one end of greenhouse 100. Hinge pin 42is a rigid cylindrical member. Hinge pin 42 is a pin for a pivotalbearing. Hinge pin 42 must be made of sturdy material able to withstandlarge amounts of pressure without defecting or bending. The outerdiameter of hinge pin 42 should be sized to make a slip fit connectionwith the inner diameter of hinge pin socket 63 on support arms 28,38.Hinge pin 42 may be made of any known material such as metal, plastic,composite, wood, or ceramic. Hinge pin could be an appropriately sizedbolt, screw, rod, bar, rivet, or other fastener. Hinge pin bracket 44holds hinge pin 42 in a stationary horizontal position about 0.5-8inches above the ground with its longitudinal axis coincident with thatof greenhouse 100. More than one hinge pin bracket may be used for thispurpose. Hinge pin 42 is typically positioned in the middle of thedoorway on the end of greenhouse 100, but hinge pin 42 could also bepositioned in the middle of the opposite end of greenhouse 100 with orwithout a doorway. Hinge pin bracket 44 can be any known type ofbracket. In best mode, hinge pin bracket 44 is a L-shaped bracket. Hingepin bracket 44 is rigidly attached to the ground or to a bracket base 46that is rigidly attached to the ground.

Spine clamp 10 is a rigid or semirigid oblong member. Spine clamp 10 hasa length that is similar to that of greenhouse 100. Spine clamp 10functions to rigidly attach both left cover or curtain 22 and rightcover or curtain 32 to the exterior of the roof of greenhouse 100. Spineclamp 10 is rigidly attached to the roof of the greenhouse 100 with itslongitudinal axis coincident with that of the ridgeline of thegreenhouse roof as depicted in the figures. Spine clamp 10 is rigidlyattached to the roof using any known means such as fasteners like bolts,screws, rivets, nails, etc. Covers or curtains 22 and 32 are eachattached to the spine clamp 10. Left cover or curtain 22 and right coveror curtain 32 could be sandwiched between spine clamp 10 and theexterior of the roof of greenhouse 100 to rigidly attach covers orcurtains 22 and 32 to greenhouse 100. Spine clamp 10 could use any knownmeans to rigidly attach to covers or curtains 22 and 32 such one or morelongitudinal friction slots in spine clamp 10 into which covers orcurtains 22 and 32 are inserted followed by wire spacers to attachcovers or curtains 22 and 32 to spine clamp 10 as with Wiggle Wire™ orwith fasteners like bolts, screws, rivets, nails, etc.

Electrical control box 50 comprises a timer, computer processor, and/orintegrated circuit with electrical continuity with a power source (notdepicted) and electrical wiring 55. Electrical wiring 55 has electricalcontinuity with left furling motor 26 and right furling motor 36.Electrical wiring 55 runs from electrical control box 50 through boththe left and right support arms 28,38 to each furling motor 26,36.Electrical control box 50 functions to send electrical power to furlingmotors 26,36 for the furling motors 26,36 to operate and function.Electrical control box 50 also functions to send electronic signals tofurling motors 26,36 to initiate them to furl and/or unfurl. Electricalcontrol box can be programmed to send a furl or unfurl signal to furlingmotors 26,36 to cause them to furl or unfurl at any time of day. Furlingcauses both left and right covers or curtains 22,32 to retractsimultaneously. Unfurling causes both left and right covers or curtains22,32 to extend into covered position simultaneously. The automaticfurling and unfurling of the covers or curtains 22,32 is the automatedaspect of the invention.

To install top furling automated retractable greenhouse cover 5 on agreenhouse 100, the hinge pin assembly 40 is installed on ground at oneend of greenhouse 100 as described above. The spine clamp is attached tothe roof of greenhouse 100 as described above. The left furling rod 24is positioned on the left side of greenhouse 100 parallel to thelongitudinal axis of the greenhouse 100 with the ends of each inalignment while simultaneously positioning the hinge pin socket 63 onthe attached left support arm 28 into hinge pin assembly 40 and placinghinge pin 42 through hinge pin socket 63 on the left support arm 28. Theright furling rod 34 is positioned on the right side of greenhouse 100parallel to the longitudinal axis of the greenhouse 100 with the ends ofeach in alignment while simultaneously positioning the hinge pin socket63 on the attached right support arm 38 into hinge pin assembly 40 andplacing hinge pin 42 through hinge pin socket 63 on the right supportarm 38. The right edge of left cover or curtain 22 is rigidly attachedto spine clamp 10. The left edge of left cover or curtain 22 is rigidlyattached to left furling rod 24. The left edge of right cover or curtain32 is rigidly attached to spine clamp 10. The right edge of right coveror curtain 32 is rigidly attached to right furling rod 34. Left andright covers or curtains 22,32 are then carefully wound or furled undertension onto furling rods 24,34. Note that the second end of leftfurling rod 24 and the second end of right furling rod 34 are notsupported or attached to a support arm so the seconds ends of furlingrods 24,34 just rest on the top of greenhouse 100 as depicted. Gravitypulls these ends down until tension from covers or curtains 22,32suspends them from spine clamp 10, so to speak.

A major benefit to the top furling design is that gravity may be used tocontinuously apply tension between the attached ends of covers orcurtains 22,32 and the furling roll as furling roll is furled andunfurled. The use of gravity is free for the use in this regard. Tensionbetween the ends of a sheet and a winding roll of itself is beneficialbecause tension keeps the sheet free wrinkles or folds and allows for atighter roll of sheeting that is easier to move and provides betterprotection for the sheeting. The top furling design of this inventionuses gravity to help furl and unfurl tightly wound rolls of cover orcurtain material 22,32.

Most greenhouses 100 are Quonset style and thus have rounded sidewalls.It is easier to furl and unfurl a cover or curtain 22,32 over a roundedsidewall. Other greenhouses are semi-gabled and thus have more straightsidewalls. It is more difficult to furl and unfurl a cover or a curtain22,32 over a straight sidewall. The straighter the sidewall, the more ofa cornered transition between the sidewall and the roof of thegreenhouse. It is more difficult to furl and unfurl around a corner thanto do so around a rounded area.

To make furling and unfurling around corners easier, the left supportarm 28 and the right support arm 38 are not each directly pivotallyattached to hinge pin assembly 40 as described above but rather are eachslideably attached to a support arm extension 60 and a support armextension spring 66, which are in turn pivotally attached to hinge pinassembly 40. Thus, top furling automated retractable greenhouse cover 5may further comprise: a first and second support arm extension 60 and afirst and second support arm extension spring 66. Each support armextension 60 is a rigid oblong cylindrical member about 0.3-8 feet longwith a top end and a bottom end. The top end of each support armextension 60 is designed to slideably attach to the bottom end of leftsupport arm 28 or to the bottom end of right support arm 38, which areidentical to each other. Slideable attachment could be accomplished by atelescopic connection with one member forming a slip fit over the othermember as depicted. The bottom end of each support arm extension 60 hasa hinge pin socket 63 located therein. Hinge pin socket 63 is acylindrical hole through support arm extension 60 that is perpendicularto the longitudinal axis of support arm extension 60. The inner diameterof hinge pin socket 63 is sized to form a slip fit with the outerdiameter of hinge pin 42. The top end of the first support arm extension60 is attached to the bottom end of left support arm 28 to form aslideable connection between these members. The top end of the secondsupport arm extension 60 is attached to the bottom end of right supportarm 38 to form a slideable connection between these members. Slideableconnection may be accomplished by any known means. The bottom end ofeach support arm extension 60 is pivotally attached to hinge pinassembly 40 with hinge pin 42 positioned through each hinge pin socket63. Each support arm extension spring 66 is a spring with a top end anda bottom end. The bottom end of each support arm extension spring 66 isattached to the hinge pin 42. The top end of the first support armextension spring is attached to the hinge pin socket 63 on the bottomend of left support arm 28. The top end of the second support armextension spring 66 is attached to the hinge pin socket 63 on the bottomend of right support arm 38.

With this configuration and design, furling rods 24,34 may extend aroundroof sidewall corners of the greenhouse 100 while furling and unfurlingaround them. Support arms 28,38 slide along support arm extensions 60 toextend the reach of the roll around the corner as the corner pulls theroll away from the hinge pin 42. After passing the corner, support arms28,38 slide back along support arm extensions 60 to retract the rollback against the sidewalls or roof as the support arm extension springs66 pull support arms 28,38 back towards the hinge pin 42 to pick up theslack.

What is claimed is:
 1. A retractable greenhouse cover or curtaincomprising: a spine clamp; a left furling cover assembly; a rightfurling cover assembly; a hinge pin assembly; an electrical control box;a first and second support arm extension where each has a top end and abottom end; and a first and second support arm extension spring whereeach has a top end and a bottom end, wherein, said spine clamp is arigid or semirigid oblong member with a roof attachment means and aflexible sheet attachment means, said left furling assembly comprises aleft cover or curtain, a left furling rod, a left furling motor, and aleft support arm, said right furling assembly comprises a right cover orcurtain, a right furling rod, a right furling motor, and a right supportarm, said hinge pin assembly comprises a hinge pin and a hinge pinbracket, said left and right covers or curtains are each rectangularsheets of material with a left edge and a right edge, said left andright furling rods each have a first end and a second end, said left andright furling motors each comprise a housing and a driveshaft, said leftand right support arms each have a top end and a bottom end, said rightedge of said left cover or curtain and said left edge of said rightcover or curtain are each rigidly attached to said spine clamp, saidleft edge of said left cover or curtain is rigidly attached to said leftfurling rod, said right edge of said right cover or curtain is rigidlyattached to said right furling rod, said left furling rod is rigidlyattached to said driveshaft on said left furling motor, said rightfurling rod is rigidly attached to said driveshaft on said right furlingmotor, said top end of said left support arm is rigidly attached to saidhousing on said left furling motor, said top end of said right supportarm is rigidly attached to said housing on said right furling motor,said hinge pin assembly is rigidly attached to the ground, said bottomend of said left support arm has a hinge pin socket that is attached tosaid hinge pin, said bottom end of said right support arm has a hingepin socket that is attached to said hinge pin, said electrical controlbox comprises a timer, computer processor, or integrated circuit withelectrical continuity with: a power source, said left furling motor, andsaid right furling motor, said bottom end of each said support armextension has a hinge pin socket located therein that is pivotallyattached to said hinge pin, said top end of said first support armextension is slideably attached to said bottom end of said left supportarm, said top end of said second support arm extension is slideablyattached to said bottom end of said right support arm, said bottom endof each said support arm extension spring is pivotally attached to saidhinge pin, said top end of said first support arm extension spring isattached said hinge pin socket on said bottom end of said left supportarm, and said top end of said second support arm extension spring isattached to said hinge pin socket on said bottom end of said rightsupport arm.